In the conventional communication system, a terminal receiver receives control and scheduling information transmitted from a NodeB before performing data demodulation, wherein the control and scheduling information is used for notifying the terminal receiver of operations to be taken, such as the information of the physical channel where downlink resources locate and coding mode, so that the terminal receiver may know in advance the scheduling information needed for receiving data, such as parameters of resource assignment and valid duration of signaling block.
In an OFDM (Orthogonal Frequency Division Multiplexing) system, since methods for allocating resources are flexible and the minimum TTI (Transmission Time Interval) required by the OFDM system is one subframe, i.e. transmission parameters vary in a very short period, currently in the OFDM system all the scheduling information and service data are transmitted together with a scheduled resource block in a same TTI.
Currently when an eNodeB (evolved NodeB) is transmitting control signaling, a large amount of control signaling and service data are together transmitted to a UE (User Equipment). However, in the large amount of control and scheduling information, some of it is to be received by the UE before the UE receives the data and only when this part of information is obtained can the UE read its own data from a corresponding downlink resource block. The terminal receiver needs to receive this part of information before demodulating the data. However, the terminal receiver cannot rely on a direction of receiving beams from the user and make the strongest end of a transmitting beam aligned with this direction by using the digital signal processing technique, i.e. this part of information cannot be beamformed.
In the current OFDM-TDD (Orthogonal Frequency Division Multiplexing-Time Division Duplex) system, the control and scheduling information is transmitted together with the service data in a downlink service slot, wherein the control and scheduling information is typically downlink control and scheduling information.
The downlink control and scheduling information includes the first type control and scheduling information, the second type control and scheduling information and the third type control and scheduling information. The first type control and scheduling information includes UE identity, resource assignment mode and valid duration of a signaling block. The second type control and scheduling information includes information of antenna, modulation mode and payload size. The third type control and scheduling information includes process number, redundancy version, new data indicator etc. of a hybrid automatic repeat need to be transmitted when an asynchronous hybrid automatic repeat mechanism is adopted; sequence number of the repeated data need to be transmitted when an asynchronous hybrid automatic repeat mechanism is adopted. The first type control and scheduling information cannot be beamformed and needs to be received by the UE before the UE receives downlink data. The second and third type control and scheduling information is UE-dedicated control and scheduling information and can be beamformed.
FIG. 1 is a schematic diagram showing a frame structure of transmitting the service data and the control and scheduling information together in the downlink service slot according to the prior art. In FIG. 1, R1 represents the first reference symbol, R2 represents the second reference symbol, D represents the service data, C1 represents the first type control and scheduling information, C2 represents the second type control and scheduling information and C3 represents the third type control and scheduling information.
The service data and the second and third type control and scheduling information need to be beamformed and the first type control and scheduling information unable to be beamformed needs to be transmitted together with the service data and the second and third type control and scheduling information in the same subframe, thus it becomes more difficult for the transmitter to process. Since the UE needs to receive the first type control and scheduling information in advance, if the first type control and scheduling information is transmitted together with the service data in the same subframe and the first type control and scheduling information is located at the foremost end of the subframe, the receiver needs to accomplish the demodulation and decoding of the first type control and scheduling information in a very short period so as to extract the scheduling information of the service data, thus it puts higher requirements for the receiver. Even the receiver adopts a method for receiving all the resources and may guarantee no data will be lost, it will increase the processing complexity of the receiver greatly and is not in favor of the design of the UE.
FIG. 2 is a schematic diagram showing an OFDM-TDD subframe according to the prior art. In FIG. 2, TS1-TS6 represent service slots, TS0 represents a downlink broadcast slot, DwPTS represents a downlink pilot slot, GP represents a guard period and UpPTS represents an uplink pilot slot. Currently, in the OFDM-TDD subframe structure, the DwPTS only carries the downlink pilot information and some frequency resources are not utilized except for a 1.25 MHz bandwidth occupied by the downlink pilot information. The amount of available resources depends on how many resources of the cell bandwidth are occupied: the more the cell bandwidth is, the more the available resources are, and thus resources are wasted and the efficiency of time and frequency transmission is reduced.
Therefore, according to the prior art, the control and scheduling information unable to be beamformed is transmitted in the downlink service slot and it increases the processing complexity of the transmitter and puts higher requirements for the receiver.
In addition, according to the prior art, only the downlink pilot information is transmitted in the DwPTS and some frequency resources are wasted so the efficiency of time and frequency transmission is reduced.